Off topic from the current discussion, but in the original Pokemon Mystery Dungeon Games (Blue, in my case) there was a chance for a dual-typed Pokemon's stats to "grow explosively" when, while in its Friend Area, is fed a Gummi that matches one of its types and is super effective against the other. Has anyone ever figured out at what rate this actually happens?
Oh yes, ZappedAmpharos on Discord/Gamefaqs noted how Gummis work
Basically the Gummi boosts your IQ based on the color type coverage
Same == 7points
Super effective against you = 4 points
Neutral = 3
Not effective = 2
Barely effective (In MD there's no type immunity) = 1
Now for Rescue Team they never considered that this would also benefit Dual types *more*, since it factors the type separately
So say you give a Clear Gummi (Ice) to Articuno. That's 7 due to Ice stab, + 4 due to Ice > Flying
In Explorers this was fixed, with the game simply using the highest points for 1 type
As for boosting the stat for all, it's always in the Friend area, never in the dungeon. And even then, it's kind of random